I've had the similar experiences, regularly. Have had PCS for 5 years now.
Stress induces your body into shut down mode and I think this causes restriction of blood flow to the brain. I use cannabis to regulate my sleep which helps me throughout the next day and levels me out.

When something big happens in my life that is stressful it takes me a few days to process it. Its like the brain is a funnel, a healthy one can pass a lot through it but an injured one can't, it can only allow so much to pass through, beyond that it gets overloaded and symptoms come back.

My only suggestion is to find an activity/ies that you enjoy that is somewhat thoughtless and mildly stimulating but passes time. You need to get your brain off of high alert which is common with PCS. There are other methods, some of which you probably do. There are also other active and passive methods like cannabis, meditation, going for a walk, mildly stimulating activities, etc. Have faith if you've made it this far its going to pass.